so that, when coupled to a massless scalar field, the classical Hamiltonian can be rewritten as [1]}, [2]}
\(\mathcal {H} &\equiv & \mathcal {H}_{\mathrm {grav}} + \mathcal {H}_{M} \nonumber \\&=& - \frac{1}{2\kappa \gamma ^2} \int \mathrm {d}^3 x \, \epsilon _{ijk} F^i_{ab} \frac{E^{aj} E^{bk}}{\sqrt{q}} + \mathcal {H}_{M},\) 
